Zeolites are crystalline aluminosilicate compositions which are microporous and which are formed from corner sharing AlO2 and SiO2 tetrahedra. Numerous zeolites, both naturally occurring and synthetically prepared are used in various industrial processes. Synthetic zeolites are prepared via hydrothermal synthesis employing suitable sources of Si, Al and structure directing agents such as alkali metals, alkaline earth metals, amines, or organoammonium cations. The structure directing agents reside in the pores of the zeolite and are largely responsible for the particular structure that is ultimately formed. These species balance the framework charge associated with aluminum and can also serve as space fillers. Zeolites are characterized by having pore openings of uniform dimensions, having a significant ion exchange capacity, and being capable of reversibly desorbing an adsorbed phase which is dispersed throughout the internal voids of the crystal without significantly displacing any atoms which make up the permanent zeolite crystal structure. Topological zeolites can be used as catalysts for hydrocarbon conversion reactions, which can take place on outside surfaces as well as on internal surfaces within the pore.
In U.S. Pat. No. 4,528,171 an EU-4 zeolite is described. The template propyltrimethylammonium hydroxide is used in the synthesis of EU-4. However, the silica to alumina ratio of the product EU-4 is higher than 49.1.
In U.S. Pat. No. 6,892,511 another zeolite, UZM-15, is described. The template propyltrimethylammonium hydroxide is used in the synthesis of UZM-15, but only as an additive to another template; and not as the sole template.
In U.S. Pat. No. 7,575,737 another zeolite, UZM-27 is synthesized with a propyltrimethylammonium hydroxide template in conjunction with calcium.
Applicants have successfully prepared a new family of materials designated UZM-37. The topology of the materials is similar to that observed for MWW. The materials are prepared via the use of a simple commercially available structure directing agent, such as propyltrimethylammonium hydroxide, using the Charge Density Mismatch Approach to zeolite synthesis (U.S. Pat. No. 7,578,993). The organoammonium compounds used to make UZM-37 zeolite are non-cyclic or contain cyclic substituents and are generally quite simple. Examples of organoammonium compounds used to make UZM-37 include propyltrimethylammonium (PTMA) and isopropyltrimethylammonium (i-PTMA) cations.
Alkylation of aromatic compounds with a C2 to C4 olefin and transalkylation of polyalkylaromatic compounds are two common reactions for producing monoalkylated aromatic compounds such as cumene and ethylbenzene. Examples of these two reactions that are practiced industrially to produce cumene (isopropylbenzene) are the alkylation of benzene with propylene and the transalkylation of benzene and a diisopropylbenzene (DIPB). The alkylation reaction forms cumene and common byproducts such as DIPBs and triisopropylbenzenes (TIPBs). DIPBs, TIPBs, and some of the higher polyisopropylbenzenes can be readily transalkylated by benzene to produce cumene. Alkylation and transalkylation reactions may be combined in one process unit in a single reaction zone or multiple reaction zones.
The UZM-37 family of materials is effective in carrying out the alkylation of aromatic with alkylating reagents. It is able to provide and maintain high conversion of olefins such as ethylene and propylene, high selectivity to mono-alkylated products such as ethylbenzene and cumene (isopropylbenzene), and high total alkylated selectivity over a range of benzene to olefin molar ratios of interest to commercial operation due to UZM-37's particular pore geometry and framework Si/Al ratio. The UZM-37 zeolite contains significant amounts of Al in the tetrahedral framework, with the mole ratio of Si/Al ranging from about 8 to about 20.